This telegraph monitor was found in an American documentation for radio amateurs from the 1970s. The indicator is a common 1 mA full-scale milliammeter.
This circuit was obtained from HAM Radio magazine in an 80's issue. The FETs are types of the time...
We found this circuit in a 1981 documentation. The circuit can still be easily assembled, as it...
This low noise audio amplifier stage uses only one transistor and has a high enough gain to...